Adding custom HTML to question add/edit form

I have added a custom field to the form using the add_filter( ‘ap_question_form_fields’, ‘my_custom_question_field’ ); filter. This works but I need to be able to add a field as an ajax auto complete.  I need users to be able to tag a record from a large DB. Too large for a select field, it needs to be ajax auto complete. I can write the code to do it but I don’t know how to make that code work with the add/edit pages.